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Feasibility of MRI-Guided Tri-Cobalt-60 IMRT for Preoperative Radiation therapy of Soft-Tissue Sarcomas
S754
International Journal of Radiation Oncology Biology Physics
Reus, Reus, Spain, 2Radiation Oncology Department, Institut Oncolo`gic del Valle`s (IOV), Barcelona, Spain, 3Radiation Oncology Department, Complejo Hospitalario Universitario de Albacete, Albacete, Spain
bone, skin, skin corridor, and PTV were compared. D25, the dose received by 25% of the target volume, inhomogeneity as per Wu et al.[(D2-D98)/ (prescription dose)*100] and R50 values were also compared. Results: The average PTV volume was 1701.25 mL (range, 813.5-3190.0). In all cases, both the clinically delivered LINAC plan and the modulated 60 Co plan covered 95% of the PTV. The mean R50 values were 2.07 and 2.42 for the LINAC and 60Co plans, respectively, while the mean PTV inhomogeneity values were 9.78 and 13.51. Dosimetric parameters for the skin corridor, in-field long bone (either the femur [n Z 3] or the tibiafibula complex [n Z 1]), and skin are shown in Table 1. Conclusions: An MRI-guided radiation therapy system utilizing modulated 60Co beams can deliver IMRT for preoperative STS with comparable dosimetry to clinically delivered LINAC-based IMRT. Even greater improvements can be achieved as MRI-guided radiation therapy allows for smaller planning margins. Based on this analysis, a clinical trial is being initiated to evaluate treatment outcomes and toxicities using modulated 60 Co IMRT. Author Disclosure: A.U. Kishan: None. M. Cao: None. D.A. Low: K. Advisory Board; Feasibility of MRI-guided Tri-Cobalt-60 IMRT for Preoperative Radiotherapy of Soft Tissue Sarcomas. P.A. Kupelian: K. Advisory Board; Scientific Advisory Board for ViewRay Inc. M.L. Steinberg: None. M.R. Kamrava: None.
Purpose/Objective(s): Non-melanoma skin cancer (NMSC) is the most frequently occurring cancer in humans. Different options currently exist to treat NMSC, such as topical treatments, surgery and radiation. The aim of this study was to analyze the outcomes, toxicity and cosmesis after patients (pts) with NMSC were treated by hypofractionated high dose rate brachytherapy (HHDR-B). Materials/Methods: 141 NMSC lesions were treated by HHDR-B. Hypofractionated treatment of 3 Gy was delivered three times a week, up to a total dose of between 45 and 54 Gy. A fixed applicator was used on 106 lesions, whereas a customized mould was used on 35 lesions. Results: With a median follow up of 24 months, local control at 2 years was 92%. Complete regression was achieved in the 96.45% of the lesions. Eleven treatment failures were observed: two partial responses, three with persistent disease, and six marginal field recurrences. Fifty-five pts (40%) had grade 2 or higher acute skin toxicity. Five patients (4.25%) had grade 4 acute skin toxicity. The cosmesis outcomes were excellent or good in 82% of pts and fair in 10% of pts. Conclusions: HHDR-B is an effective and well-tolerated treatment for non-melanoma skin cancer. Author Disclosure: M. Arenas: None. M. Arguı´s: None. L. Dı´ez-Presa: None. I. Henrı´quez: None. M. Murcia-Mejı´a: None. M. Gasco´n: None. D. Go´mez: None. A. Lafuerza: None. E. Mur: None. S. Sabater: None.
3381 Feasibility of MRI-Guided Tri-Cobalt-60 IMRT for Preoperative Radiation therapy of Soft-Tissue Sarcomas A.U. Kishan, M. Cao, D.A. Low, P.A. Kupelian, M.L. Steinberg, and M.R. Kamrava; University of California, Los Angeles, Los Angeles, CA Purpose/Objective(s): Contouring of extremity soft tissue sarcomas are best accomplished using MRI guidance. Challenges exist with accurately fusing MRI with CT simulation images as the patient is often in different positions. The ability to simulate, plan, and treat using MRI alone presents an opportunity to improve treatment for this group of patients both in terms of target definition and minimizing daily treatment variations. We hypothesized that a modulated MRI-guided cobalt 60 (60Co) planning system could create IMRT plans that approximate linear accelerator (LINAC) based plans. Materials/Methods: The primary study population consisted of four patients with lower extremity sarcoma who were treated with pre-operative IMRT to 50 Gy in 25 fractions in our department within the last year. Target volumes were contoured as per the recent consensus guidelines from Haas et al. CTV to PTV expansion was 5 mm. A commerciallyavailable MRI-guided tri-60Co planning system was used to generate IMRT plans based on the same dosing schema and contours. A skin corridor was defined as a volume 180 degrees from the center of the PTV, encompassing 30-40% of the circumference of the extremity. Doses to the
Scientific Abstract 3381; Table Selected Average Dosimetric Parameters for LINAC and Modulated Cobalt-60 IMRT Plans (n Z 4)
Skin Corridor D25 (Gy) Mean Dose (Gy) Max Dose (Gy) Long Bone D25 (Gy) Mean Dose (Gy) Max Dose (Gy) V40 (%) Skin D1cc (Gy)
LINAC Plans
Modulated Cobalt-60 Plans
19.0 13.6 40.7
23.2 17.4 36.9
36.6 25.5 48.6 31.5
35.1 25.0 53.6 34.1
52.3
56.5
3382 Acute Skin Toxicity Using High-Dose-Rate Electronic Brachytherapy for Nonmelanoma Skin Cancer M.K. Cheung, Y. Kim, S.E. Sckolnik, J.L. Grow, B.G. Slane, J.D. Gordon, and B. Stea; University of Arizona, Tucson, Arizona, AZ Purpose/Objective(s): High Dose Rate Electronic Brachytherapy (HDREBT) is an alternate treatment modality for patients with non-melanomatous skin cancers who are not candidates for surgery. This study seeks to identify and characterize factors associated with treatment toxicity using this radiation modality. Materials/Methods: Retrospective review of 33 patients with 50 lesions treated at our institution from April 2011-May 2013 was performed with IRB approval. All lesions were pathologically confirmed malignant basal (56%) or squamous (44%) cell carcinoma. Median age was 76 years (range: 43-92) and median tumor size was 1cm (range: 0.2cm-3cm). A HDR-EBT system delivered a median BED of 60Gy (a/b Z 10; range: BED 6.3-69.6Gy/2-29fx) to a depth of 0.1-0.5cm using an appropriate sized applicator (range: 1-5cm diameter). Treatment toxicity was evaluated using the RTOG/EORTC Acute/Late Radiation Morbidity Scoring Criteria. Results: Local control is 100% with a median follow-up of 3.6 months. Acute grade 3 moist desquamation developed in 9 of the treated lesions (18%). Acute grade 4 ulceration manifested in 3 lesions in the lower extremity (6%) and 1 lesion on the upper lip (2%) and occurred a median of 23 days from the start of treatment. Table 1 compares the acute toxicities between lower extremity vs head and neck (HN) sites (ear, eyelid, nose, and scalp). The proportion of lesions developing acute grade 2-3 toxicity was similar between the two groups (47.1% vs 48.5%), but a greater proportion of acute grade 4 toxicity developed in lower extremity lesions (17.6% vs 3.0%). There was also a greater proportion of acute grade 4 toxicity in lesions treated with fraction size 500cGy vs 70, p Z 0.10), treatment depth (2mm vs >2mm, p Z 0.22), number of treatment fractions (21 days, p Z 010). One patient developed late grade 4 toxicity with a non-healing ulcer in the lower extremity 3.4 months after completion of treatment.
Scientific Abstract 3382; Table
Toxicity Grade Grade Grade Grade Grade
1 2 3 4
Acute Toxicity by Lesion Location
Lower Extremity Lesions (n Z 17)
Head and Neck Lesions (n Z 33)
6 (35.3%) 8 (47.1%) 0 (0.0%) 3 (17.6%)
16 (48.5%) 7 (21.2%) 9 (27.3%) 1 (3.0%)
Fisher Exact Test P Z .009
International Journal of Radiation Oncology Biology Physics
Reus, Reus, Spain, 2Radiation Oncology Department, Institut Oncolo`gic del Valle`s (IOV), Barcelona, Spain, 3Radiation Oncology Department, Complejo Hospitalario Universitario de Albacete, Albacete, Spain
bone, skin, skin corridor, and PTV were compared. D25, the dose received by 25% of the target volume, inhomogeneity as per Wu et al.[(D2-D98)/ (prescription dose)*100] and R50 values were also compared. Results: The average PTV volume was 1701.25 mL (range, 813.5-3190.0). In all cases, both the clinically delivered LINAC plan and the modulated 60 Co plan covered 95% of the PTV. The mean R50 values were 2.07 and 2.42 for the LINAC and 60Co plans, respectively, while the mean PTV inhomogeneity values were 9.78 and 13.51. Dosimetric parameters for the skin corridor, in-field long bone (either the femur [n Z 3] or the tibiafibula complex [n Z 1]), and skin are shown in Table 1. Conclusions: An MRI-guided radiation therapy system utilizing modulated 60Co beams can deliver IMRT for preoperative STS with comparable dosimetry to clinically delivered LINAC-based IMRT. Even greater improvements can be achieved as MRI-guided radiation therapy allows for smaller planning margins. Based on this analysis, a clinical trial is being initiated to evaluate treatment outcomes and toxicities using modulated 60 Co IMRT. Author Disclosure: A.U. Kishan: None. M. Cao: None. D.A. Low: K. Advisory Board; Feasibility of MRI-guided Tri-Cobalt-60 IMRT for Preoperative Radiotherapy of Soft Tissue Sarcomas. P.A. Kupelian: K. Advisory Board; Scientific Advisory Board for ViewRay Inc. M.L. Steinberg: None. M.R. Kamrava: None.
Purpose/Objective(s): Non-melanoma skin cancer (NMSC) is the most frequently occurring cancer in humans. Different options currently exist to treat NMSC, such as topical treatments, surgery and radiation. The aim of this study was to analyze the outcomes, toxicity and cosmesis after patients (pts) with NMSC were treated by hypofractionated high dose rate brachytherapy (HHDR-B). Materials/Methods: 141 NMSC lesions were treated by HHDR-B. Hypofractionated treatment of 3 Gy was delivered three times a week, up to a total dose of between 45 and 54 Gy. A fixed applicator was used on 106 lesions, whereas a customized mould was used on 35 lesions. Results: With a median follow up of 24 months, local control at 2 years was 92%. Complete regression was achieved in the 96.45% of the lesions. Eleven treatment failures were observed: two partial responses, three with persistent disease, and six marginal field recurrences. Fifty-five pts (40%) had grade 2 or higher acute skin toxicity. Five patients (4.25%) had grade 4 acute skin toxicity. The cosmesis outcomes were excellent or good in 82% of pts and fair in 10% of pts. Conclusions: HHDR-B is an effective and well-tolerated treatment for non-melanoma skin cancer. Author Disclosure: M. Arenas: None. M. Arguı´s: None. L. Dı´ez-Presa: None. I. Henrı´quez: None. M. Murcia-Mejı´a: None. M. Gasco´n: None. D. Go´mez: None. A. Lafuerza: None. E. Mur: None. S. Sabater: None.
3381 Feasibility of MRI-Guided Tri-Cobalt-60 IMRT for Preoperative Radiation therapy of Soft-Tissue Sarcomas A.U. Kishan, M. Cao, D.A. Low, P.A. Kupelian, M.L. Steinberg, and M.R. Kamrava; University of California, Los Angeles, Los Angeles, CA Purpose/Objective(s): Contouring of extremity soft tissue sarcomas are best accomplished using MRI guidance. Challenges exist with accurately fusing MRI with CT simulation images as the patient is often in different positions. The ability to simulate, plan, and treat using MRI alone presents an opportunity to improve treatment for this group of patients both in terms of target definition and minimizing daily treatment variations. We hypothesized that a modulated MRI-guided cobalt 60 (60Co) planning system could create IMRT plans that approximate linear accelerator (LINAC) based plans. Materials/Methods: The primary study population consisted of four patients with lower extremity sarcoma who were treated with pre-operative IMRT to 50 Gy in 25 fractions in our department within the last year. Target volumes were contoured as per the recent consensus guidelines from Haas et al. CTV to PTV expansion was 5 mm. A commerciallyavailable MRI-guided tri-60Co planning system was used to generate IMRT plans based on the same dosing schema and contours. A skin corridor was defined as a volume 180 degrees from the center of the PTV, encompassing 30-40% of the circumference of the extremity. Doses to the
Scientific Abstract 3381; Table Selected Average Dosimetric Parameters for LINAC and Modulated Cobalt-60 IMRT Plans (n Z 4)
Skin Corridor D25 (Gy) Mean Dose (Gy) Max Dose (Gy) Long Bone D25 (Gy) Mean Dose (Gy) Max Dose (Gy) V40 (%) Skin D1cc (Gy)
LINAC Plans
Modulated Cobalt-60 Plans
19.0 13.6 40.7
23.2 17.4 36.9
36.6 25.5 48.6 31.5
35.1 25.0 53.6 34.1
52.3
56.5
3382 Acute Skin Toxicity Using High-Dose-Rate Electronic Brachytherapy for Nonmelanoma Skin Cancer M.K. Cheung, Y. Kim, S.E. Sckolnik, J.L. Grow, B.G. Slane, J.D. Gordon, and B. Stea; University of Arizona, Tucson, Arizona, AZ Purpose/Objective(s): High Dose Rate Electronic Brachytherapy (HDREBT) is an alternate treatment modality for patients with non-melanomatous skin cancers who are not candidates for surgery. This study seeks to identify and characterize factors associated with treatment toxicity using this radiation modality. Materials/Methods: Retrospective review of 33 patients with 50 lesions treated at our institution from April 2011-May 2013 was performed with IRB approval. All lesions were pathologically confirmed malignant basal (56%) or squamous (44%) cell carcinoma. Median age was 76 years (range: 43-92) and median tumor size was 1cm (range: 0.2cm-3cm). A HDR-EBT system delivered a median BED of 60Gy (a/b Z 10; range: BED 6.3-69.6Gy/2-29fx) to a depth of 0.1-0.5cm using an appropriate sized applicator (range: 1-5cm diameter). Treatment toxicity was evaluated using the RTOG/EORTC Acute/Late Radiation Morbidity Scoring Criteria. Results: Local control is 100% with a median follow-up of 3.6 months. Acute grade 3 moist desquamation developed in 9 of the treated lesions (18%). Acute grade 4 ulceration manifested in 3 lesions in the lower extremity (6%) and 1 lesion on the upper lip (2%) and occurred a median of 23 days from the start of treatment. Table 1 compares the acute toxicities between lower extremity vs head and neck (HN) sites (ear, eyelid, nose, and scalp). The proportion of lesions developing acute grade 2-3 toxicity was similar between the two groups (47.1% vs 48.5%), but a greater proportion of acute grade 4 toxicity developed in lower extremity lesions (17.6% vs 3.0%). There was also a greater proportion of acute grade 4 toxicity in lesions treated with fraction size 500cGy vs 70, p Z 0.10), treatment depth (2mm vs >2mm, p Z 0.22), number of treatment fractions (21 days, p Z 010). One patient developed late grade 4 toxicity with a non-healing ulcer in the lower extremity 3.4 months after completion of treatment.
Scientific Abstract 3382; Table
Toxicity Grade Grade Grade Grade Grade
1 2 3 4
Acute Toxicity by Lesion Location
Lower Extremity Lesions (n Z 17)
Head and Neck Lesions (n Z 33)
6 (35.3%) 8 (47.1%) 0 (0.0%) 3 (17.6%)
16 (48.5%) 7 (21.2%) 9 (27.3%) 1 (3.0%)
Fisher Exact Test P Z .009